The purpose of this project is to utilize the sensitivity and specificity of gas chromatography-mass spectrometry to study problems related to mental health. Our present investigations entail administering 18O2 to rats and following its incorporation into tyrosine and then into dopamine and its metabolites. BIBLIOGRAPHIC REFERENCES: Neff, N.H., Galli, C.L. and Costa, E.: The turnover of dopamine: Studies with 18O2. In Costa, E. and Giacobini, E. (Eds.): Advances in Biochemical Psychopharmacology. Vol. 16, New York, Raven Press, 1977, pp. 187-192. Galli, C.L., Commissiong, J.W. and Neff, N.H.: Measuring the formation of the biogenic amines utilizing 1802 Biochem. Pharmacol., in press, 1977.